NOMENCLATURE FOR ORGANIC CHEMICAL TRANSFORMATIONS docx

Pure
&
Appl.
Chem.,
Vol.
61,
No.
4,
pp.
725-768, 1989.
Printed in Great Britain.
@
1989 IUPAC
INTERNATIONAL UNION
OF
PURE
AND APPLIED CHEMISTRY
ORGANIC CHEMISTRY DIVISION
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY*
NOMENCLATURE FOR ORGANIC
CHEMICAL TRANSFORMATIONS
(Recommendations
1988)
Prepared
for
publication by
R. A. Y. JONES'
and
J.
F.
BUNNETT2

'School
of
Chemical Sciences, University
of
East Anglia, Norwich NR4 7TJ, UK
'Division
of
Natural Sciences
11,
University
of
California, Santa Cruz,
CA
95064,
USA
*Membership of the Commission during the period 1976-87 in which the report was prepared
was as follows (T, Titular Member; A, Associate Member; N, National Representative):
P. Ahlberg (N, 1980-87; T, 1987-; Sweden); T. A. Albright
(N,
1985-1987;
A,
1987-; USA);
E.
M. Arnett (T, 1985-87; USA); A.
T.
Balaban (N, 1981-87; Romania); J.
F.
Bunnett
(T, 1973-1983; Chairman, 1978-83; A, 1983-85; USA); A. R. H. Cole (A, 1974-79; Australia);
M. P. Doyle (A, 1979-87;

T
and Secretary 1987-; USA);
W.
Drenth (N, 1984-87;
A,
1987-;
Netherlands);
V.
Gold?
(T,
1973-81, 1983-85; Chairman, 1983-85; A, 1981-83; UK); R. D.
Guthrie (A, 1977-87; USA);
E.
A. Halevi (T, 1981-; Israel); J. J.
E.
Humeres A. (N, 1983-85;
Brad); G. Illuminati? (T, 1977-85; Italy);
W.
P. Jencks (T, 1981-85; USA);
X.
Jiang (N, 1980-;
China); R. A. Y. Jones (A, 1977-81; T and Secretary, 1981-87; A, 1987-; UK); P. Laszlo
(N, 1985; Belgium); J.
S.
Littler (A, 1979-87; UK);
J.
March (A, 1977-87; USA);
J.
M.
McBride (T, 1987-; USA); D. J. McLennan

(N,
1982-; New Zealand);
M.
L.
MihailoviC
(N, 1979-85; Yugoslavia);
V.
I. Minkin (A, 1987-; USSR); P. Miiller (A, 1981-85; T and
Chairman, 1985-; Switzerland);
0.
M. Nefedov (T, 1981-; USSR); M. N6grBdi (N, 1980-87;
Hungary); M. Oki (T, 1985; Japan); J. R. Penton (T and Secretary, 1973-81; A, 1981-85;
Switzerland); M.
J.
Perkins (T, 1977-81; UK);
J.
Reedijk (A, 1977-81; Netherlands);
C. Riichardt (T, 1973-77; FRG); K. Schwetlick (T, 1977-85; A, 1985-; GDR); A. Streitwieser
(T, 1973-77; A, 1977-81; USA); M. Tisler (N, Yugoslavia; 1985);
J.
Toullec (T, 1973-81;
A, 1981-85; France); P. van Brandt (N, 1982-85; A, 1985; Belgium); J. Vaughan (N, 1980-82;
New Zealand); Z. ZBvada
(N,
1985; Czechoslovakia);
J.
Zdysiewicz (N, 1985-; Australia);
H.
Zollinger (T, 1973-79; Chairman, 1973-78; Switzerland).
?

Deceased
The Commission gratefully acknowledges the help given in the preparation
of
this report by the
following chemists, who were members of one or more working parties.
I.
Agranat (Israel); R.
L.
Augustine (USA);
S.
H.
Bertz (USA); D. Hellwinkel (Germany);
R.
W.
Hoffman (Germany); K. N. Houk (USA); R. M. Kellog (Netherlands);
G.
W.
Klumpp
(Netherlands); G. A. Kraus (USA);
S.
Moon (USA); A. Panaye (France); D.
E.
Pearson
(USA);
D.
P. N. Satchel1 (UK).
Republication of this report is permitted without the need for formal IUPAC permission
on
condition that an
acknowledgement, with full reference together with IUPAC copyright symbol

(0
1989
IUPAC), is printed.
Publication of a translation into another language is subject to the additional condition of prior approval from the
relevant IUPAC National Adhering Organization.
Nomenclature for organic chemical transformations
(Recommendations
1988)
Abstract
These rules provide
a
general system of nomenclature for transformations whereby one
organic compound is converted into another. A
transformation
is distinct from a
reaction
in
that it describes only those changes that are involved in converting the structure of
a
substrate
into that of
a
product, regardless of the reagent or the precise nature of the substrate, or (with
some exceptions) the mechanism.
Thus
all processes in which X-H
is
converted into
X-NO2 are examples of the single transformation called “nitration”, whatever the
nature

of
X, and irrespective ofwhether the reaction entails the replacement of by
N02+,
of
H’
by
NOz’,
or
of H- by N02
The
basis
of the
names
of all transformations is that they provide
a
description of the
conversion of substrate into product by giving
a
string or strings of the names of groups or
entities that become attached to and/or detached from the substrate, followed by a
sumX
that
describes the nature of the transformation. Straightforward examples are self-explanatory; for
example:
“hydro,chloro-addition”;
“dibromo-elimination”;
“hydroxy-de-iodo-substitution”.
For many transformations, particularly substitutions, simplified names are recommended for
use in speech or writing (by contrast to the more detailed indexing names).
Thus

“hydroxy-
de-iodination” may be used instead of
“hydroxy-de-iodo-substitution”,
or “nitration” instead
of
“nitro-de-hydro-substitution”.
A list of non-systematic names is given for transformations
that are too complex to be named by the present systematic
mles.
CONTENTS
Preamble
1 Introduction
2
Classes
of
transformation
3
Recognition of the “substrate”
4
Desirable characteristics in names
5
Site designation
6
Mechanistic information
7
Naming entities and groups
8
Provisional publication
General rules applicable to the names of all transformations
0.1

Construction of names
0.2
Priority
0.3
Site designation
0.4
Inversion of names for indexing
Rules for substitution transformations
1.1
Univalent substitutions
1.2
Multivalent substitutions
Rules for addition transformations
2.1
2.2
Multivalent additions
Addition of two univalent groups
Rules for elimination transformations
3.1
3.2
Multivalent eliminations
Elimination of two univalent groups
Rules for attachment and detachment transformations
4.1
Attachment transformations
4.2
Detachment transformations
727
73
1

732
736
74
1
745
Rules for simple rearrangement transformations
5.1 Scope of the rules
5.2
5.3
[x,y] Sigmatropic rearrangements
5.4
Migration accompanied by substitution
5.5
747
Migrations unaccompanied by any other transformations
Migration accompanied by addition, elimination, attachment,
detachment, or other transformation
726
Nomenclature for organic chemical transformations
727
6
Rules for coupling and uncoupling transformations
6.1 Scope of the rules
6.2 Coupling transformations with detachment
6.3 Coupling transformations with attachment
6.4
6.5 Uncoupling transformations
Coupling transformations with attachment and detachment
7 Rules for insertion and extrusion transformations
7.1 Insertion transformations

7.2 Extrusion transformations
8
Rules for ring closing and ring opening transformations
8.1 General information
8.2 Intmolecular cyclisation transformations
749
752
154
8.3 Non-fragmenting ring opening transformations
8.4 Intermolecular cyclisation transformations
8.5 Fragmenting ring opening transformations
9
Complex transformations 761
Appendix Transformations accomplished by some name reactions 766
PREAMBLE
1
Introduction
These recommendations provide a general system of nomenclature for transformations whereby one organic
compound is converted into another. Except for substitution transformations, for which systematic names have been
employed since
1954
1,
these processes have lacked systematic verbal representation. Some have been chamcterised
either
as
“name reactions” (e.g., Michael reaction) or by various and sometimes inconsistent descriptive terms but
often they have been represented only by an equation or
a
relatively cumbersome multi-word description.
Several transformations have well-established non-systematic names, for example “hydration”, “lactonization”,

“hydrolysis”. It is not intended that the names defined by the present recommendations should displace these
common terms. However, many such names are used erroneously (“hydrogenation” in place of “hydrogenolysis”) or
ambiguously (“bromination” for both substitutions and additions), and it is desirable that such confused usage should
be discontinued.
A
transformation
must be distinguished from a
reaction.
The full description of
a
reaction would state
or
imply
all the reactants used and all the products formed. In
a
transformation one
is
concerned only with changes in one
particular species designated
as
the “substrate”
(see
below). Thus, “nitration” refers to
a
process in which
a
hydrogen
atom of substrate X-H is replaced by
a
nitro group to give X-NO2, irrespective of whether the reagent is

HNO,,
N2O5, NOz’BF4-
or
EtON02.
In representing
a
transformation the substrate should appear alone on the left of the arrow that denotes the change, and
only products that are described by the transformation should appear to the right. For example:
C6H6
-
C6H5-N02
A representation of the following type describes
a
reaction and should not
be
used for
a
transformation:
C6H6
+
N02+
-
qH5-NO2
+
H+
In this document, when it
is
desired to draw attention to
a
reagent its formula is placed in parentheses over the arrow:

(NO*+)
c&
-
C~HS-NO~
2
Classes
of
transformations
In
the development
of
these recommendations, it
was
necessary
to
recognize several
classes
of transformations.
Classes recognized and defined here briefly
2
include
the
following:
Atracbmears
,
in which
the
substrate species becomes attached to another species through covalent bond formation
at
a

single atom of each species, without
loss
of any atom
or
group from the substrate.
Deraclimenrs
,
in which
the
substrate species loses
a
fragment through mpture of
a
single
or
multiple covalent bond
between
two
atoms, without the acquisition of any other atom
or
group.
728
COMMISSION
ON
PHYSICAL ORGANIC CHEMISTRY
Substitutions,
In univalent substitutions
a
univalent atom or group replaces
a

univalent atom or group. In
multivalent substitutions,
a
multiply-bonded atom or group or more than one atom or group is replaced by a multiply-
bonded atom or group or more than one atom or group.
Additions,
in which one
or
more pairs of atoms or groups, alike or unalike within any pair, become attached to
different atoms of
an
unsaturated substrate or to
a
single substrate atom
as
in a carbene or nitrene.
In
contrast to
a
usage sometimes employed, transformations in which one chemical species becomes attached to another through
covalent bond formation between
a
single atom of one and
a
single atom of the other are called
anachments,
not
additions.
Eliminations,
in which

two
or more atoms or groups are detached from different positions of
a
substrate
so
as
to
form or extend an unsaturated system, or from a single site
so
as
to form
a
carbene, nitrene or similar entity. In
contrast to
a
usage sometimes employed, transformations in which one chemical species fragments into two by
rupture of the covalent linkage between two atoms are called
detachments,
not eliminations.
Simple rearrangements,
in which a group changes its point of attachment, whether or not accompanied by any
other transformation.
Insertions,
in which
a
divalent atom or group is inserted between two covalently bonded atoms to form a product in
which those two atoms are bonded to the inserted atom or group.
Extrusions,
in which two atoms covalently bonded to an atom or group become bonded directly to each other with
concomitant

loss
of the previously interposed atom or group.
Besides these rather simply defined categories, there are some which, although chemically no more complex, pose
special problems of nomenclature. These include
ring-opening
and
ring-closing
transformations, and also
coupling
and
uncoupling
transformations, in which identical moieties become joined or separated with the
concomitant loss
or
gain of other atoms or groups.
Moreover, some transformations are of such chemical complexity
as
to make the systematic naming of them
a
formidable and possibly unprofitable
task.
Such complex transformations are collected in
a
list of non-systematic but
carefblly defined names.
3
Recognition of the “substrate”
When two or more chemical species are involved in
a
reaction, it is often obvious which should be designated the

“substrate”, that is, the principal substance on which the other reagent(s) are considered to operate. In other
cases
it is
less obvious. Thus,
in
the reaction of aniline with benzoyl chloride to form N-phenylbenzamide, either reactant
seems an equally probable choice
as
substrate. This single
reaction
comprises two distinct
fmsfomations:
replacement of the chlorine atom of benzoyl chloride by an anilino group, and of a hydrogen atom of aniline by a
benzoyl group. These recommendations provide separate names for the two transformations, and do not attempt to
name the reaction
as
a
whole. The choice of which transformation to name, which is equivalent to choosing one
reactant
as
the
substrate,
is
made with reference to the context.
It is
a
cardinal principle of these recommendations that the name of the transformation is independent of the nature of
the substrate.
Thus
any

transformation in which
an
X-H
bond is replaced by an
X-NOz
bond is “nitration”.
4
Desirable characteristics in names
Two mther different purposes are served by systematic names for transformations. One is indexing and the retrieval
of information, and the other communication in speech and writing. Rather different criteria need to be met if
names
are to be satisfactory for the two purposes.
For indexing, names must
be
definitive. Though simplicity in
a
name is always
a
virtue, there is no requirement that
indexing
names
be short, or that they avoid interposed letters or numbers; also, they may use punctuation marks to
specify certain types of information.
Names for
use
in
speech should be relatively short and euphonious, and should contain features distinctive to the
ear.
They should
be

easily adapted into other major languages of science. Ideally the
names
for specific transformations
should
be
precise, but some sacrifice of precision
can
be tolerated in order to satisfy the above criteria if no serious
ambiguity results.
A
name that is difficult to pronounce or for the ear to comprehend is likely to be avoided in speech,
and is therefore of little worth for
oral
communcation. Names for use in effective written discourse must meet similar
criteria, for similar reasons.
For either purpose, there
is
need both for specific names that portray single transformations and for generic
names
that
portray
sets
of closely related transformations.
Thus,
there
is
need for
a
name to represent the category of substitution
reactions in which

an
alkoxy group replaces
a
halogen atom, but also for a name to represent the specific case in
which an ethoxy group replaces
a
bromine atom. These recommendations provide for both.
Some of the transformations falling within the scope of these recommendations are of such complexity
that
even the
“speechlwriting”
names
for them are too unwieldy to be of other than limited value unless visual aid is also provided
(e.g. Example
2
of Rule
8.5.3).
Such limitations are recognized and are inherent in the application of any
rules
of
systematic chemical nomenclature.
Nomenclature for organic chemical transformations
729
5
Site designation
In the naming of transformations it is often necessary to designate the
relative
locations of reacting sites
of
substrates.

The commonly used indices for reacting sites are Greek letters and arabic numerals, but use of either to designate
relative sites can in particular cases lead to ambiguities. Thus, it could be confusing to speak of 1,4-addition to the 9-
and 10-positions of anthracene,
or
a,a-elimination from the 0-position of 0-bromostyrene. Accordingly these
recommendations employ for relative site designation post-slashed arabic numerals. Instead of writing
“
1,4-dibromo-
addition” the
relative
nature of the site designations is indicated by writing
‘‘
1/4/dibromo-addition”. In speech the
slash symbols are not pronounced.
In
casual
speech and writing one may wish to refer to
a
specific substrate and to modify the site designations
accordingly, using absolute rather than relative numbering.
For
example the lM/dibromo-addition to 2,4-hexadiene
could be called “2,5-dibromo-addition”. Such usage, however, violates the principle enunciated above that the name
of
a
transformation is independent of the substrate and it is therefore not
a
formal part of the nomenclature.
The elements of the reacting sites of substrates are denoted by italicised atomic symbols,
as

in 0,C-dihydro-addition
(to a carbonyl group).
For
transformations involving only carbon sites the atomic symbols are omitted. Where
relative site numbers and atomic symbols are both used, the symbol is placed after the slash
-
for example,
1/0,3/N-
dihydro-addition (to an azoxy compound).
6
Mechanistic information
The naming of transformations is distinguished from the designation of
reaction
mechanisms.
Often
two
or
more
distinctly different mechanisms for the same transformation are indicated by experimental evidence,
or
are
conceivable, and views
as
to what mechanism prevails may be in dispute
or
may change with time. The names for
transformations provided by these recommendations do not include information about reaction mechanism.
For
example, one could hypothesise that the conversion of benzene to nitrobenzene entails the replacement
of

H+
by
NO2+,
of
H’
by
NOz’,
or
even of
H-
by
NOz
In each case the
transfornation
is the same. The chemist who
wishes to indicate a mechanism
can
do
so
by adding appropriate parenthetic adjectives
or
phrases; e.g., “nitration
(via
nitronium ions)”, but such amplification is not a formal part of the nomenclature. (See examples 10 and 11 under
Rule 1.1
.)
Similarly the stereochemical aspects of a transformation are not formally part of the name, but may be
incorporated parenthetically
as,
for example, in

“(syn)dibromo-addition”.
(See examples 4 and
5
under Rule 2.1.1
.)
One type
of
mechanistic information should, however, be acknowledged in the naming of transformations. That
is
knowledge of what bonds break
or
form during
a
reaction.
For
example, to name the hydration of benzonitrile to
benzamide
as
though it involved replacement of the cyano group by a carboxamido group would be
a
travesty. The
name given to a transformation should be in accord with knowledge
as
to the changes of connectivity that occur.
In
some cases the same overall result may be achieved by quite different means. Thus, transformation of ally1
benzoate to propyl benzoate can be performed either by dihydroaddition (of
H2)
to the olefinic linkage,
or

by
propoxy-de-allyloxylation
(with propanol). To name these
two
processes identically would be more detrimental than
helpful.
Subtle variations in reaction conditions
can
sometimes alter the pattern of connectivity change.
Thus,
l-methyl-2-
butenyl hydrogen phthalate is hydrolyzed
in
weakly alkaline solutions with scission of the alkyl-oxygen bond but in
concentrated alkaline solutions with scission of the acyl-oxygen bond. In such
a
case
one might wish to employ
different names for the transformation to distinguish different routes,
or
one might justifiably use either name if
distinguishing between them happened not to be important in
a
particular context,
or
not feasible.
7
Naming entities and groups
A
transfornation may involve one or more attachments

or
detachments of entities to
or
from
a
substrate. Some
transformations
can
be accurately described only by specifying the oxidation level of an entity.
For
example, the
attachment of
NO2+
to benzene to form a cationic Wheland intermediate is
a
different transformation from the
attachment of
N02’
to form
C&5N02’.
It is therefore necessary to use different names for the different oxidation
levels
(N02+,
nitrylium
or
nitronium;
NOz’,
nitryl;
NOz-,
nitrite).

On
the other hand,
as
discussed above in section
6,
“Mechanistic Information”, some transformations (substitutions, additions, eliminations)
can
in principle be
accomplished by reagents of different oxidation levels.
In
naming these transformations
an
entity should if possible
be given
a
name that does not specify the oxidation level (nitro, for example)
so
as
not to imply
a
particular
mechanistic path. In such
a
case the entity is referred to
as
a
“group”. Tables
1
-
4

give illustrative lists of
names
of
entities and groups: it will be seen that suitably distinctive names are not always available.
8
Provisional publication
Some of these recommendations, namely, those dealing with univalent substitution, addition and elimination
transformations, were provisionally published in 198 1
3.
730
COMMISSION
ON
PHYSICAL ORGANIC CHEMISTRY
TABLE
1.
oxidation level
*
An
illustrative list of names of entities of specified oxidation level and of groups of unspecified
X
cation
(X+)
radical
(X’)
anion
(X-)
group
(X-)
H
CH3

w
CH3CO
HOCO
CH3CO2
H2N
C~HSNH
H2N-NH
;b
NO2
HO
CH30
OCN
F
HS
CH3S
CH3S02
HOS02
CH3SO3
CIS02
hYb
methylium
phenylium
acetylium or
ethanoylium
carboxylium
acetoxylium or
ethanoyloxylium
aminylium
phenylaminylium
hydraziiylium

or
hydrazylium
nitrosylium or nitrosonium
nitrylium
or
nitronium
hydroxylium
methoxylium
fluomylium
SUlfanyliUm
methylsulfanylium
methanesulfonylium
hydroxysulfonylium
chlorosulfonylium
methanesul fonyloxylium
hydrogent
methyl
phenyl
CYrnYl$
acetyl
or
ethanoyl
carboxyl
acetoxyl
or
ethanoyloxyl
aminyl
phenylaminyl
hydraziiyl
or

hYdrazyl
azidyl
nitrosyl
nitryl
hydroxyl
methoxyl
fluorine?
sulfanyl
methylsulfanyl
methanesulfonyl
hydroxysulfonyl
chlorosulfonyl
methanesulfonyloxyl
hYQide
methanide
benzenide
cyanide
I-oxoethanide
carboxylide
acetate
or
ethanoate
mi&
phenylamide
hydraziideor
hychazi&
azide
nitrite
hydroxide
methoxide

cyanate
fluoride
sulfmide
methylsul fanide
methanesuhate
hydrogen sulfite
chlorosulfite
methanesulfonate
hydro
methyl
phew1
cyan0
(-0
isocyano
(-NC)
acetyl
or
ethanoyl
acetoxy
or
ethanoyloxy
amino
phenylamino
or
anilino
hydrazii
addo
nitroso
nitro
(-NY

nitrito
or
nitrosooxy
(+NO)
hYbW
methoxy
cyanato
(CNO)
isocyanato
(-NCO)
fluoro
sulfanyl
or
mercapto
methylthio
or
methylsulfanyl
methylsul fonyl
sulfo
chlorosulfonyl
methylsul fonyloxy
csrboxy
*
Many of these names
am
based
on draft recommendations currently
Wing
prepared by the Commissions on the Nomenclahue of Inorganic
and

Organic Chemistry,
11.2
and
III.1
respectively.
t
Strictly these names should
be
monohydrogen, monofluorine, but the simpler alternatives
are
normally adequate.
$
In
naming
some transformations it may
be
desirable to name an entity
as
if it
had
the structure of a specified canonical
form:
thus, if the
cyanyl radical attaches to a substrate via the nitrogen atom, the name “isocyanyl” may
be
used
(see
Rule
4.1.1
and Examples

8
and
10
tlmmderr).
TABLE
2.
An
illustrative list of names of
charged groups of unspecified oxidation level and
of some related entities of specified oxidation level.
-CH2- methanidyl
-C02- carboxylato C02 carbon dioxide
-NH-
amidyl
-0-
oxido
02-
oxide
-02-
peroxido
02
dioxygen
-pO32- phosphonato
-NH3+
ammonio
NH3
ammonia
-OH,+ oxonio H20 water
-Nz+
diazonio

N2 &nitrogen
TABLE
3.
and
of
groups with more than one univalent point of attachment,
and of related entities of specified oxidation level.
An
illustrative list of
names
of multivalent groups
‘CH2
-NH
-0
-CH2-
>CH-CH3
-NH-
-0-0-
NH
”2
CH2
0,
methylidene
imino
diazo
methylene
or
methanediyl
ethane-
1,l

-diyl
aminediyl
or
imino
peroxy
or
dioxidanediyl
methylene
or
carbene
aminylene
or
nitrene
dioxygen
OX0
-CHCH3
-NOH
=N
-S
-CH<
-CH2CH2-
-S-
NR
S
CR2
TABLE
4.
An illustrative list of names of silicon and phosphorus
groups.
~~

eth ylidene
h ydroxyimino
Ntrilo
thioxo
methanetriyl
ethylene
sulfanediyl
or
thio
carbene (generic)
nitrene (generic)
sulfur
-SiMe3 trimethylsilyl -0-SiMe3 trhnethylsilyloxy
or
trimethylsiloxy
-SiMe2-
dmethylsilanedi yl -SiH20SiH2- disiloxane- 1,3-diyl
-PH2
phosphanyl
or
phosphino
-Pb AS-phosphanyl
or
phosphoranyl
-P(O)Me2 dimeth ylphosphino yl
-0-PMe2 dimethylphosphanyloxy
-P(O)(OH)2 phosphono
-m3*
phosphonato
Nomenclature for organic chemical transformations

731
0
GENERAL RULES APPLICABLE
TO
THE NAMES
OF ALL TRANSFORMATIONS
0.1
substrate into product by listing the names of groups that become attached to the substrate
or
detached from it
or
that
migrate from one site to another, and by the use of positional
locants
and of words and/or syllables that give
information about the nature of primitive changes (defined in reference
2)
occurring within the transformation and
about the class of the transformation.
0.1.1
groups, their names are separated by commas. The major components of the name, that is, the different strings of
group names, their positional locants, and informative words and syllables, are separated by hyphens. Exceptionally:
(a) neither
a
hyphen nor
a
comma is used after
a
post-slashed arabic numeral (Rule
0.3),

and (b) in simple
speechlwriting
names
hyphens may be omitted if clarity is not thereby diminished.
0.1.2 The name of any complex group
or
entity may be enclosed in square brackets for clarification.
0.1.3
In
a
transformation in which groups
or
entities are both attached to and detached from the substrate, those
that are attached are listed first, followed by the syllable “-de-”, followed by those that are detached.
0.2
Priority. When more than one group or entity is present in a string, the order
is
defined by
two
criteria: (a)
groups
or
entities are listed in order of increasing valence
(in
this context, “valence” means the number of formal
covalent bonds to that group or entity from the rest of the molecule); (b) groups
or
entities of the same valence
are
listed in order of increasing priority

as
defined (for univalent groups
or
entities) by the Cahn-Ingold-Prelog rules4 or
(for groups
or
entities of higher valence) by the principles of those
rules.
Examples:
1
hydroxy (-OH) is listed before
0x0
(-0)
2
carboxy
(-COOH) is listed before fluoro
(-F)
3
1-fluoroethyl (-CHFCH3) is listed before 1-chloroethyl (-CHClCH3)
4
hydroxymethyl (-CH20H) is listed before formyl (-CHO)
5
formyl
(-CHO)
is listed before dimethoxymethyl (-CH(OCH3)2)
6
phenylimino (-NPh) is listed before 0x0
(-0)
When
groups

or
entities are named generically their priority is that of the lowest-priority member of the
Construction
of
names.
In
general the names for
a
transformation describe the conversion of
If there is more than one group within any one of the categories of attaching, detaching, or migrating
0.2.1
genus.
Examples:
1
The priority of the genus “halogen”
is
defined by that of fluorine.
2
The priority of the genus “alkoxy” is defined by that of methoxy.
0.3
Site
designation. In transformations that entail connectivity changes at more than one site of the
substrate the relative positions of substrate atoms are denoted by post-slashed arabic numerals, numbered
consecutively from the prime site which is designated
I/.
Unless specifically ruled otherwise, the prime site is
selected by applying the following criteria in order.
(a)
(b)
(c)

A
site from which detachment occurs is numbered
I/
in preference to
a
site to which attachment occurs.
The prime site is selected
so
that
as
low a number
as
possible appears
at
the first point in the name of a
transformation at which the assigned numbers would differ.
The prime site is selected
so
that at the first point of difference the lower number is associated with
a
substrate atom of higher atomic number.
1
criterion (a).
In allylic substitutions (Rule
1.4)
the site of the leaving group is designated
l/.
2
Criterion (b). In perhydroaddition to EtCH-CHON (Example
1

under Rule
2.2.2.4),
it is the nitrogen
atom that is designated
1/,
giving the numbering sequence
1/1/2/2/3/4/.
If the
fl
carbon atom were the
prime site, the sequence would be
1/2/3/3/4/4/.
However, in perhydroaddition to EtCeCCH-NH the
0
carbon atom is designated
I/
and the nitrogen is
4/.
Criterion (c). In perhydroaddition to CH2=C-O (to give CH~-CHZ-OH), it is the oxygen atom that
is
designated
I/
rather than the methylene carbon atom.
Examples:
3
In some speecwwriting names it may be permissible to omit site designations: such occasions are referred to
specifically in subsequent rules.
0.3.1
sites are designated by italicised atomic symbols. Unless specifically ruled otherwise, these symbols are located
as

follows: (a) if connectivity changes
occur
only at one site of the substrate, then the symbol is placed at the
start
of the
name; (b) if connectivity changes involve the cleavage
or
formation of
a
bond between
two
sites of the substrate,
as
in
insertion and extrusion transformations and ring opening and closing transformations, the symbols for the atoms
at
each end of the bond are placed at the
start
of the name; (c) otherwise the symbol is placed immediately after the post-
slashed arabic numeral denoting the position of the site.
In speecwwriting names the atomic symbol
C
may be omitted if ambiguity does not ensue.
In
simple transformations
in which the context makes their nature obvious, it may be permissible to omit all atomic symbols: such occasions
are
referred to specifically in subsequent rules.
When one
or

more of the reacting sites of the substrate is an element other than carbon, then all the maing
732
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
0.4
indexing, placing the term that characterises the type of transformation at the front of the name.
Example:
Inversion
of
names
for
indexing. Any transformation name may be inverted for the purposes of
Ph3P
-
Ph3C-OH
hydroxide-attachment (according to Rule 4.1)
attachment, hydroxide (inverted for use in an index)
1
SUBSTITUTION TRANSFORMATIONS
1.1
Univalent-univalent substitutions. These are transformations in which a univalent atom
or
group is
replaced at the same site by another univalent atom
or
group.
1.1.1
For
SpeecWwriting, the name comprises (a) the name of the entering group, (b) the syllable “-de-”, (c) the
name
of

the leaving group, and (d) the suffix “ation”.
For
euphony
or
to accord with traditional usage, slight changes
in spelling may be made at the end
of
the name of the leaving group.
1.1.2
For
indexing, the name comprises (a) the name of the entering group, (b) the syllable “-de-”, (c) the name
of the leaving group, and (d) the suffix “-substitution”.
(Attention is called to the difference in the endings between speecWwriting and indexing names for substitutions.
Justification for this difference stems in part from general considerations stated
in
the Preamble, in
part
from the fact
that
the “ation” suffix for substitution names has been in use since 1954, and in part from the utility of the suffix
“substitution”
in
indexing names in their inverted form (Rule 0.4). Indexing names may be used in speech
or
writing
if one wishes to do
so.)
1.1.3
Introduction or replacement
of

hydrogen. Hydrogen of natural
or
unspecified isotopic abundance
is represented
as
“hydro”, except that when a leaving group it is represented
as
“hydrogen” in speecwwriting names.
(See examples 4,5,6 and
7.)
When a distinction is made between isotopes of hydrogen 5,1H is represented
as
“protio”,
For
speecwwriting, specific mention of hydrogen
as
an
entering or leaving group may optionally be omitted. If
hydrogen is the entering group, the name then comprises (a) the syllable “de”, (b) the name of the leaving group, and
(c) the
suffix
“ation”. (Example
7.)
If hydrogen is the leaving group, the name comprises (a) the name of the entering
group and (b) the suffix “ation”. (Examples 4,
5,
and 6.) In either case, for euphony slight changes in spelling may
be made at the end of the name of the group. In this usage it would
be
normal to omit hyphens before

or
after “de”.
1.1.4
Naming
of
groups. Leaving groups are named
as
they are in the substrate: entering groups
as
they are
in the product.
Examples:
BS
“deuterio” and 3H
as
“tritio”. (See example 6.)
1
CH3CH2Br
-
CH3CH20CH3
SpeecWwriting: specific: methoxy-de-bromination
Indexing:
2
Ph-N2+
SpeecWwriting:
Indexing:
generic: alkoxy-de-halogenation
specific:
methoxy-de-bromo-substitution
generic:

alkoxy-de-halo-substitution
-
Ph-I
specific: iodo-de-diazoniation
generic: halo-de-diazoniation
specific:
iodo-de-diazonio-substitution
generic:
halo-de-diazonio-substitution
3
CH3CH2CH2Br
-
CH3CH2CH2CH(COOEt)2
SpeecWwriting:
bis(ethoxycarbony1)methyl-de-bromination
Indexing:
bis(ethoxycarbony1)methyl-de-bromo-substitution
4 CH2(COOEt)2
-
CH3CH2CH2CH(COOEt)2
SpeecWwriting: specific: propyl-de-hydrogenation
or
propylation
Indexing: specific:
propyl-de-hydro-substitution
generic: alkyl-de-hydrogenation
or
alkylation
generic:
alkyl-de-hydro-substitution

Speedwriting: specific:
bromoacetyl-de-hydrogenation
or
bromoacetylation
generic: acyl-de-hydrogenation
or
acylation
Indexing: specific:
bromoacetyl-de-hydro-substitution
generic:
acyl-de-hydro-substitution
Nomenclature for organic chemical transformations
733
6
C6H6
-
C6HsNO2
SpeecWwriting: nitro-de-hydrogenation or nitration
Indexing:
nitro-de-hydro-substitution
If it
is
desired to distinguish among hydrogen isotopes, the following names could be used.
SpeecWwriting: nitro-de-protiation, nitro-de-deuteriation, nitro-de-tritiation
Indexing:
nitro-de-protio-substitution,
etc.
I
cH3qcH3
-

CH3qcH3
S020H
H
Speechlwriting: hydro-de-sulfonation or desul fonation
Indexing:
hydro-de-sulfo-substitution
8
,CO-CH,
Ph-NH-CO-CH,
-
Ph-N
‘NO
Speechlwriting:
N
-nitroso-de-hydrogenation
or N-nitrosation
Indexing:
N
-nitroso-de-hydro-substitution
9a &Cl
-
GNH2 9b @c1 NO2
-
qC1
NO
2
c1
c1
C1 NH2
Both processes are examples of the same transformation, namely:

Speechlwriting: amino-de-chlorination
Indexing:
amino-de-chloro-substitution
However, in
casual
usage in speech or writing (see section
5,
“Site Designation”,
in
the Preamble) one
may wish to make
a
distinction between the
two
by saying:
for 9a: 2-amino-dechlorination
for 9b 4-amino-dechlorination
of
2,4-dichloronitrobenzene
I
10
The transformation is
ethylthio-de-bromination
(for speechlwriting) or
ethylthio-de-bromo-substitution
(for indexing). Either may be followed by “(with inversion of configuration)”.
(R)-sec-butyl bromide
-
(S)
-sec-butyl ethyl sulfide

11
((EtO),FCINa+)
The transformation is
diethoxyphosphinoyl-de-iodination
(for speechlwriting) or diethoxyphosphinoyl-de-
iodo-substitution (for indexing).
A
chemist might wish to convey more information
as
well
as
an
opinion
about mechanism by stating that it is photo-induced
diethoxyphosphinoyl-de-iodination
(probably by the
S,,
1
mechanism).
PhI
Ph-PO(OEt)Z
1.2
same site of
a
multivalent atom or group and/or of more than one atom or group. For example, they include the
following general categories:
Multivalent-multivalent substitutions. These are transformations involving the replacement at the
-
R-Y
/w

‘X
R-X
-
R-Y R=X
-
R
The “multiplicity” of such a transformation is defined
as
the number of formal covalent bonds from the substrate that
are broken or made. Note that this rule embraces transfonnations (such
as
the hydrolysis
of
a nitrile to a carboxylic
acid) which are not mechanistically simple substitutions.
Except for the usage described in Rule 1.2.2, simultaneous substitutions at
two
or more different sites are regarded
as
separate transfonnations; each must be named separately.
734
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
1.2.1
(b) the syllable “-de-”, (c) the name(s) of the leaving group
or
groups, (d) a term to denote the multiplicity of the
substitution, namely “-bi”, “-ter”, “-quater”, etc., and (e) the suffix “substitution”.
1
.2.2
number of identical univalent groups, then in speechlwriting only it may

be
named by
using
the appropriate
multiplying prefix
“bis
-”,
“Wk-”
,
“
tetdis
-”,
etc., in italics followed in parentheses by the name of the
corresponding univalent-univalent transformation
as
described in Rule 1.1.
This
form of nomenclature may, if
desired,
be
extended
to
include simultaneous transformations at separate sites.
(See
examples 1-3.)
Examples:
For
both
SpeecWwriting and indexing the name comprises (a) the name(s) of the entering group
or

groups,
If a transformation involves the substitution of
two
or
more identical univalent leaving groups by the same
1
CHzClz
-
CH2(0Et)2
Specific:
diethoxy-de-dichloro-bwubstitution
Generic:
dialkoxy-de-dihalo-bisubstitution
For
speecwwriting the following are also permissible:
Specific:
Generic:
bis
-(alkoxy-de-halo-substitution),
bis
-(alkoxy-de-halogenation)
bis
-(
ethoxy-de-chloro-substitution),
bis
-(
ethoxy-de-chlorination)
2
CH2BrCI
-

CH2(0Et)2
Specific:
diethoxy-de-chloro,bromo-bisubstitution
Generic:
dialkoxy-de-dihalo-bisubstitution
The optional speecWwriting forms are applicable only to the generic name, and are identical to thcse given
in
Example 1.
3 CI(CH2)4CHC12
-
MeS(CH2)4CH(SMe)2
For
indexing this must
be
named
as
two separate transformations:
methylthio-de-chloro-substitution
and
di[methylthio]-de-dichloro-bisubstitution
For
speecWwriting it is permissible (but not obligatory) to name it
as:
tris
-(methylthio-de-chlorination)
4
(Ph3PCHz)
CH3CHO CH~CHPCH~
Specific:
methylene-de-0x0-bisubstitution

Generic:
alkylidene-de-oxo-bisubstitution
5
(MeNHOS020H)
RzC-NPh R2C=N+-Me
I
0-
Specific:
[N-methyl-N-oxidoiminio]-de-phenylimino-bisubstitution
Generic:
[
N-alkyl-N-oxidoiminio]-de-arylimino-bisubstitution
6
C6H5CHO
-
C@$H(OEt)2
Specific:
diethoxy-de-0x0-bisubstitution
Generic:
dialkoxy-de-0x0-bisubstitution
Note that this and the following example Ire not named
as
additions if
(as
is normal) the carbonyl oxygen
atom is not incorporated into the product (see section
6,
“Mechanistic Information”, in the Preamble).
7
CbH5CHO

-
C6H5CHCIOEt
Specific:
ethoxy,chloro-de-0x0-bisubstitution
Generic:
alkoxy,halo-de-oxo-bisubstitution
8
(CH3COOH)
CH2N2 CH3OCOCH3
Specific:
hydro,acetoxy-de-diazo-bisubstitution
Generic:
hydro,acyloxy-de-diazo-bisubstitution
9
c6HscHBrc1
-
C6HsCHO
Specific:
0x0-de-chloro,bromo-bisubstitution
Generic:
0x0-de-dihalo-bisubstitution
10 C~HSNH~
-
C&IsN‘CHC,$5
Specific:
benzylidene-de-dihydro-bisubstitution
Generic:
alkylidene-de-dihydro-bisubstitution
11 C6HsCHO
-

C~H~CH-NC~HS
Specific:
phenylimino-de-0x0-bisubstttution
Generic:
arylimino-de-oxo-bisubstitution
Nomenclature for organic chemical transformations
735
12 CH3CN
-
CH3COOH
hydroxy,oxo-de-nitrilo-tembstitution
13 CSCl2
-
co2
Specific:
dioxo-de-dichloro,thioxo-quatembstitution
Generic:
dioxo-de-dihalo,thioxo-qwtersubstitution
14
(MeMgI)
Specific:
Sb-pentamethyl-de-pentachloro-quinquesubstitution
Generic:
Sb-pentaalkyl-de-pentahalo-quinquesubstitution
SbCl5
b
SbMe5
15
PhSF5
-

PhSO2OH
Specific:
S
-hydroxy,dioxo-de-pentafluoro-quinquesubstitution
Generic:
S
-hydroxy,dioxo-de-pentahdo-quinquesubstitution
1.3
“Aggregating” substitutions. These are transformations in which
an
identical leaving group from each of
two
or
more identical substrate entitites is replaced by a single multivalent incoming group to form
a
product in which
the remaining
parts
of the substrate entities are all equivalent; that is, they are transformations of the type:
2A-X
-
A2Y
or
3A-X
-
A3Z etc.
These transformations could be named by Rule 1.1
as
“AY-de-X-substitutions”
or

“A2Z-de-X-substitutions”,
but
such names disguise the symmetry of the transformation. To emphasise this the “aggregating” nomenclature
described below is used. (Compare also the discussion of coupling and uncoupling transformations, Rule 6.1.)
1.3.1
“-de-”, (c) the name of the leaving group preceded by the appropriate multiplier for the number of substrate entities
(di-, tri-, tetra-), (d) the suffix “aggre-substitution”.
Examples:
The name of
an
“aggregating” substitution comprises: (a) the name of the entering group, (b) the syllable
1 2 C2H50H
-
(
C2H,O),CH,
0
-methylene-de-dihydmaggre
-substitution
2 C6H5I
-
C~HS-CH~-CH?- C6H5
ethylene-de-diiodo- aggre -substitution
2
3 2 CH3Br
-
CH3-O-O-CH3
peroxy-de-dibromo-agp -substitution
4 2ArH
-
ArS-Ar

thio-de-dihydro-aggre -substitution
5
3 CH30H
-
(CH30)3CCH3
0
-ethanylidyne-de-trihydro-aggre
-substitution
6 4PhSH
-
(PhS)4C
S
-methanetetrayl-de-tetrahydro-aggre
-substitution
1.4
group becomes attached
to
a site different from that which bore the leaving group, but in which there is no other
change of connectivity in the substrate. This rule does not, therefore, include transformations such
as
the cine-
substitution of a halogenobenzene, which is covered in Rule
5.
These transformations are named according to Rules 1.1 and 1.2, with the addition of a post-slashed arabic numeral to
indicate the site of the incoming group relative to that of the leaving group, which
is
taken implicitly
as
11.
Examples:

Allylic and related substitutions. These are substitution transformations in which the incoming
1 CH2=CH-CHMe-Br
-
HO-CH2-CH-CHMe
Speechlwriting:
3lhydroxy-de-bromination
Indexing:
3lhydroxy-de-bromo-substitution
2 CH2-CH-O-CMe3
-
CH3-CH-0
SpeecWwriting:
3/hydro-de-Otert-butylation
Indexing: 31 C-hydro-de-0-tert -butyl-substitution
Speechlwriting: 5/chloro-de-bromination
Indexing:
5/chloro-de-bromo-substitution
736
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
2
ADDITION TRANSFORMATIONS
2.1
univalent atoms
or
groups (called addends) become attached to an unsaturated substrate. These transformations
include addition to simple olefins, to carbonyl groups, to aldimines and ketimines, to dienes, to aromatic
or
heteroaromatic substrates, to acetylenes, to carbenes and nitrenes, to 1/3/dipolar intermediates, and others of similar
kind.
Addition

of
two univalent groups. These rules deal with transformations
as
a result ofwhich
two
2.1.1
Addition to
a
single olefinic or acetylenic linkage.
2.1.1.1
The indexing name comprises (a) the locant 1/ and the name of the addend of lower priority
as
defined
in
Rule 0.2, (b) the locant 2/ and the name of the addend of higher priority, and (c) the
sumX
“-addition”. Groups are
named according to Rule 1.1.4. (See examples 2,3,6,7 and
8.)
2.1.1.2
If the two addends are the same, the name comprises (a) the locants 1/2/, (b) the syllable “di”
or
“bis”
(as
appropriate
6),
(c) the name of the addend, and (d) the suffix “-addition”. (See examples 1 and
4.)
2.1.1.3
In speecWwriting names the locants 1/, 2/ and the hyphens may be omitted.

Examples:
1
CH~ECH-CH~-CH~OCH~
-
BrCH,-CHBr-CH,CH,OCH,
Speecldwriting: dibromoaddition
Indexing: 1/2/dibromo-addition
2a CH3-CH-CH2
-
CH3-CHBr-CH3
2b CH3-CH-CH2
-
CH3-CH2-CH2Br
Both transformations are:
SpeecWwriting: hydro,bromo-addition
Indexing: lhydro ,2/bromo-addition
In casual use in speech and writing (compare section 5,“Site Designation”, in the Preamble) one may wish
to make
a
distinction between the two by saying:
for 2a: 1-hydro-2-bromoadditon
for 2b: 2-hydro- 1-bromoaddition
to propene
1
3
(CF,OOCl)
CH2cCH2 ClCH2CH2OOCF3
1/[ trifluoromethylperoxy], 2/chloro-addition
4
(Cl>

02,
CH3COOH)
~IZUIS-CH~CH’CHCH~ meso-CH3CHCl-CHClCH3
Speecldwriting: dichloroaddition
Indexing: 1/2/dichloro-addition
One could introduce
a
parenthetic description of stereochemistly (see section 6, “Mechanistic
Information”, in the Preamble) by writing:
(anti)
1/2/dichloro-addition.
5a
(Brz,CH,OH)
(Z)-pent-2-ene
threo-2-bromo-3-methoxypentane
5b
(Brz,CH30H)
(Z)-pent-2-ene
.
erythro-2-bromo-3-methoxypentane
5C
(Brz,CH,OH)
(Z)-pent-2-ene
threo-3-bromo-2-methoxypentane
5d
(Br2,CH30H)
(Z)-pent-2-ene
erythro-3-bromo-2-methoxypentane
All these processes are examples of a single transformation, namely:
specific: methoxy-bromo-addition

or
I/methoxy-2/bromo-addition
Generic: alkoxy,halo-addition
or
l/alkoxy,2/halo-addition.
In casual usage additional information could be given
as
in
the following examples:
For 5a and 5c:
For 5a and 5b:
For 5d:
(anti)
l/methoxy,2/bromo-addition
3-methoxy,2-bromo-addition
to (Z)-pent-2-ene
(syn
)2-methoxy,3-bromo-addition
to (Z)-pent-2-ene
6 HCsCH
-
CH2-CHCl
hydrochloroaddition
or
l/hydro,2/chloro-addition
Nomenclature
for
organic chemical transformations
737
7a

(anti)
HCiCPh
-
(E)-RS02-CH=CPh-Br
(SP)
HCgCPh
-
(Z)-RS02-CH-CPh-Br
7b
For la:
(anti)alkylsulfonyl,bromo-addition
or
(anti)
l/alkylsulfonyl,2/bromo-addition
For lb:
(syn)alkylsulfonyl,bromo-addition
or
(syn)l/alkylsulfonyl,2/bromo-addition
8
NH2 H
Both transformations are examples of:
In casual use in speech and writing a distinction may be made by saying:
hydro-amino-addition or lhydro-2/amino-addition
2-hydro, 1-amino-addition or
l-hydro,2-amino-addition
to 4-chlorobenzyne
1
I/[
tribromomethyl],2/bromo-addition
In

casual
usage (compare section
5,
“Site Designation”,
in
the Preamble) one could describe the process
as
photoinitiated
l-[tribromomethyl],2-bromo-addition
of CBr4 to oct-1-ene by a radical mechanism.
2.1.2 Addition
to
multiple bonds involving heteroatoms. Names are formulated
as
under Rule 2.1.1
save that the names of the addends are preceded by italicised atomic symbols of the sites of addition.
If
the addends
are identical the substrate sites are numbered in order of decreasing atomic number. (Rule
0.3;
see
example 7.)
In speechlwriting names atomic symbols may be omitted if the context makes clear the nature of the transformation.
Examples:
1
CH3CHO
-
CH3CH(OH)CN
SpeecWwriting:
0

-hydro, C-cyano-addition
Indexing: 1/
0
-hydro, C-cyano-addition
or hydro,cyano-addition (if the context makes clear that the addition is to
C-0)
2 OH
I
(CH3)2C-O
-
(CH3)2C-CH2-CO-CH3
SpeecWwriting: hydro,acetonyl-addition (to acetone)
Indexing: 11
0
-hydro,2/
C-[2-oxopropyl]-addition
Note: In these Recommendations systematic structural nomenclature is normally used in indexing names.
3
AKHO
-
AKH(OH)CH2N02
SpeecWwriting:
Indexing: 11
0
-hydro,Z/C -nitromethyl-addition
0
-hydro,C-nitromethyl-addition
or
hydr0,nitromethyl-addition
(to beddehyde)

4 OH
I
I
PhCOCH3
-
Ph C CH3
SO3-
SpeecWwriting:
Indexing:
0
-hydro, C-sulfonato-addition or
hydro,sulfonato-addition
(to acetophenone)
11
0
-hydro,2/
C
-sulfonato-addition
5
(CH30CH2)2CmO
-
(CH30CH2)2C(OH),
Speecwwriting:
Indexing: 11
0
-hydro,2/ C-hydroxy-addition
0
-hydro, C-hydroxy-addition or hydro,hydroxy-addition (to
a
carbonyl group)

738
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
For
transformation of acetone to intermediate:
SpeecWwriting: generic: metallo,alkyl-addition (to acetone)
Indexing: generic:
l/O-metallo,2/C-alkyl-addition
For
transformation of intermediate to
final
product (Rule 1.1):
SpeecWwriting: generic: 0-hydro-de-metallation
Indexing: generic:
0-hydro-de-metallo-substitution
For
transformation of acetone to final product:
SpeecWwriting: generic: hydro,alkyl-addition (to acetone)
Indexing: generic: 1/
0
-hydro,2/C-alkyl-addition
specific: l/O-lithio, 2/C-[
1-(phenylthio)cyclopropyl]-addition
specific: 0-hydro-de-lithiation
specific:
0-hydro-de-lithio-substitution
specific: 1/
0
-hydro, 2/C-[
1-(phenylthio)cyclopropyl]-addition
7

CH3CHO
-
CH3-CH2-OH
SpeecWwriting:
Indexing:
1/0,2/C-dihydro-addition
8
PhCN
-
PhC-NMgI
0,C-dihydro-addition or dihydroaddition (to acetaldehyde)
I
CH3
Speedwriting: specific:
C-methy1,N-iodomagnesio-addition
or
methyl jodomagnesio-addition (to benzonitrile)
generic:
N-metallo,C-alkyl-addition
generic: l/N-metallo,2/
C
-alkyl-addition
Indexing: specific: 1/ C-methyl,2/ N-iodomagnesio-addition
Note that the Rule for designating the priorities of generic names (0.2.1) results in a difference between the
specific and generic names in the order of listing the addends according to Rule 2.1.1.1. Such anomalies
are uncommon but, occasionally, unavoidable. In Example
9
specific and generic priorities are the same.
9
PhNO

-
PhzNOLi
SpeecWwriting: specific:
0
-1i thio
,
N-phenyl-addition
generic:
0-metallo,N-aryl-addition
Indexing: specific: 1/0
-lithio,2/N-phenyl-addition
generic: 1/
0
-metallo,2/N-aryl-addition
10
(adamantane-2-thiol)
SpeecWwriting: generic: C-hydro, S-alkylthio-addition
Note that it is not desirable to omit atomic symbols, because they distinguish this transformation from the
formation of a dithiohemiacetal.
Indexing: specific: 1/ C-hydro,Y
S
-[2-adamantylthiol-addition
adamantane- 2-thione bis(2-adamantyl) disulfide
generic: 1/ C-hydro,Z/S dkylthio-addition
2.1.3
linkage, except that for speecwwriting it is usually desirable to emphasize the character of the transformation by
including the locants “1/”,“1/” and, for nitrenes, the atomic symbols.
(For
indexing they are requisite.)
Examples:

Addition to
a
carbene or
a
nitrene.
The rules are the same
as
for addition to a single olehic
1 C12C
-
C12CHOCH3
lhydro, Umethoxy-addition
2 EtOOC-N
-
EtOOC-NH-C(CH3)3
1/ N-hydro, 1/
N-
tert-butyl-addition
3
(cyclohexane)
4
C1
(Me3SnSnMe3)
I
I
CClBr
.
MejSnCSnMe3
CH3CH
CH3CH2-C6H1

1
1 hydro, 1 /cyclohexyl-addition
Br
specific:
l/l/bis(trimethylstannyl)-addition
generic: l/l/distannyl-addition
Nomenclature for organic chemical transformations
739
2.1.4
Addition to conjugated, cumulative
or
other extended unsaturated substrates.
2.1.4.1
If addition occurs only across
two
adjacent atoms or to a single centre (e.g. a carbene
or
nitrene), then
Rules 2.1.1 to 2.1.3 apply: the remainder of the unsaturated substrate
is
irrelevant to the name of the transformation,
Examples:
1 CH3_CH=CH-CH=CH-CH3
-
CH3-CHBr-CHBr-CH-CH-CH3
112ldibromo-addition
2
I
I
3 CH2-CH-NC

-
CH,=CH-N-CH-N
3
Ihydro, llpiperidino-addition
2.1.4.2
When the addends attach to sites that are separated by one
or
more atoms, then that
part
of the unsaturated
substrate that undergoes addition is numbered consecutively with post-slashed arabic numerals, atom
11
being the site
to which the first-named addend is attached (Rule 0.3). With this modification, Rules 2.1.1 to 2.1.3 are then applied.
(Rule 2.1.1.3 is not applicable.) Changes in the location of x-bonds are not specifically described in the name of the
transformation.
It
is usually undesirable to omit the atomic symbol for a heteroatom, but the symbol
C
may be omitted
in
speechlwriting names if
no
ambiguity ensues.
(See
Example
5.)
Examples:
1 CH3-CH-CH-CH-CH-CH3
-

CH3-CHBr-CH-CH-CHBr-CH3
ll4ldibromo-addition
,053
(Na/EtOH/NH,),
6
1
14ldihydro-addition
2 OCH3
3 CH~ZCH-CH=CH~
-
CH3-CH=CH-CH,CI
1
/hydro,4/chloro-addi
ti
on
4
(EtSH)
EtSCH-N-CH-CH2
-
(EtS)2CH-N-CH-CH3
Ihydro,4/ethylthio-addition
5
H
Speechlwriting:
lhydro,41O-lithio-addition
Indexing:
11
C-hydro,4/0-lithio-addition
6
CH3

lhydro-3lmethoxy-addition
OCH3
+-
7
[
Ph-C-N-CH-C6H4-N02
-
Ph-C-N-CH-C6H4-N02]
-
P~-C-N-CH~-C&H,-NO~
I
lfhydro,3/chloro-addition
c1
11
N-hydro-3lC-chloro-addition
C1 H
740
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
2.2
addends andor more than two univalent addends add to
an
unsaturated substrate. The multiplicity of these
transformations is defined
as
one half of the combined valences of the addends.
These transformations include additions to alkynes, nitriles, and other substrates containing triple bonds, and to
conjugated and cumulative dienes and other multiply-unsaturated substrates. Except for the usage described in Rules
2.2.1.2 and 2.2.2.4, simultaneous additions to two
or
more isolated double bonds are regarded

as
separate
tmformations; each must be named separately.
The speecWwriting
names
are the same
as
the indexing names unless otherwise stated.
2.2.1
two divalent addends, or of one divalent and two univalent addends. The name comprises (a) the names of the
addends
in
order of increasing valence, groups of the same valence being given in order of increasing priority (Rule
0.2), each name being preceded by the appropriate site designation, and (b) the suffix “-biaddition”.
2.2.1.1
If the first-named addend (if divalent) or the first
two
(if univalent) attach to position 11 and the remaining
addend
or
addends attach to position 21, then in speechtwriting names the positional numbers may optionally be
omitted. In speechlwriting the atomic symbol
C
may be omitted if
no
ambiguity ensues.
2.2.1.2
If a biaddition involves the addition of two identical pairs of univalent addends to two non-cumulative
double bonds, each between an identical pair of atoms, then in speecwwriting only it may
be

named by using the
italicised prefix
“bis
-”
followed
in
parentheses by the name of the corresponding mono-addition
as
described in Rule
2.1. This form of nomenclature may be extended to include simultaneous additions to isolated double bonds.
(Example 10, and see Example 4 under Rule 2.2.2.)
Examples:
Multivalent additions. Rules under this heading deal with transformations
in
which multivalent
Additions
of
multiplicity two (biadditions). These are additions of four univalent addends, or of
(RuO~)
1 CH3C=CCH3 CH3COCOCH3
Speechtwriting: dioxobiaddition
Indexing: 1/2/dioxc-biaddition
2 CH3CsCH
-
CH3COCH3
Speechtwriting: dihydro,oxo-biaddition
Indexing: 11
l/dihydro,2/oxo-biaddition
3
CH3C;N

-
CH3CONH2
Speechtwntmg:
NN-dihydro,C-0x0-biaddition
Indexing: 1/
l/N-dihydr0,2/C-oxo-biaddition
Note: In this example the optional omission of the letter
C
from the speechtwriting name is not
recommended; the emphasis of
NN
at the beginning of the name needs to be counteracted.
4 CH3NC
-
CH3NH-CHO
Speechtwriting:
l/N,2-dihydro,2-oxo-biaddition
Indexing: 1/N ,2/C-dihydro,2/ C-0x0-biaddition
Note: In the speechtwriting name the positional numbers are not optional (Rule 2.2.1.1).
5
PhN=C=NPh
-
PhNH-CS-NHPh
Speechtwriting:
l/N,3/N-dihydro,2/thiono-biaddition
Indexing:
l/N,3/N-dihydr0,2/C-thiono-biaddition
6
PhC=CH
-

PhCBr2-CH3
SpeecWwriting:
dihydro,dibromo-biaddition
Indexing:
l/l/dihydro,2/2/dibromo-biaddition
7
PhClCH
-
PhCHzCH3
Speechtwriting: tetrahydrobiaddition
Indexing: 11
1/2/2/tetrahydro-biaddition
CH(OH)CH3
lhydro, 1
I[
1 -hydroxyethyl] ,2/oxo-biaddition
Note: In this example, and in all cases where any of the addends have other simple names, it is
recommended that the positional numbers
be
always included.
9
(CH3CHO)
CH3-CmC-OCH3
-
CH3-C-CO-OCH3
II
CHCH3
SpeecWwriting:
ethylidene,oxo-biaddition
Indexing:

l/ethylidene,2/oxo-biaddition
Nomenclature for organic chemical transformations
741
10
CH3CH-CH-CH-CH-CH3
__*
CH3CHCI-CH2-CHCl-CH2CH3
Indexing
or
speechlwriting:
1/3/dihydro,2/4/dichloro-biaddition
Speechlwriting only*:
bis
-(hydro,chloro-addition)
[*
Rule 2.2.1.21
11
(HCN)
Speechlwriting:
1/0,3Idihydro,2/4/dicyano-biaddition
Indexing:
PhCHSCH-CHO
-
PhCH( CN)CH$H(OH)CN
11 0,31
C
-dihydro,Z/C ,4/ C-dicyano-biaddition
12 CH3CO-CH=NOH
-
CH3CH(OH)-CH2NHOH

Speechlwritingor indexing: 1/0,2/C ,31C,4/N -tetrahydro-biaddition
Note: The letter
C
is used differently in examples
1
1 and 12. When only the 11 atom is not carbon there
is little ambiguity in omitting
C.
In the present example, however, “2/3141W could be thought to imply
that atoms
21
and 31 were nitrogen.
Additions of multiplicity greater than
two
are named by analogy with the Rule (2.2.1) for
2.2.2
biadditions with appropriate changes to the numerical prefixes. Additions of multiplicity three, four, five, etc, are
named teradditions, quateradditions, quinquadditions, etc, respectively.
2.2.2.1 Post-slashed arabic locants should always be used, except
as
laid down in Rule 2.2.2.3.
2.2.2.2 If the atom designated
11
is the only heteroatom in the unsaturated substrate, then for speechlwriting the
symbol
C
for the other atoms may be omitted. (See examples
1
and 3.)
2.2.2.3 If, in

an
addition with multiplicity greater than two,
all
the addends are identical and the product of addition
is fully saturated, then
in
speechlwriting the transformation may optionally be named using (a) the prefix “per”, (b)
the name
of
the addend followed by
a
hyphen, and (c) the suffix “addition”. (Example
1
,)
2.2.2.4 The usage described in Rule 2.2.1.2 may be extended to more than two non-cumulative double bonds by
using the appropriate multiplying prefix,
“
tris-”,
“tetmkis
-”,
etc.
Examples:
1
EtCH-CHCN
-
EtCH2CH2CH2NH2
Speechlwriting:
Indexing:
2 CH2-C=CH-CH-C-CH2
-

CH3-CHBrCHBr-CHBrCHBr-CH3
Speechlwriting or indexing:
1/2/5/6/tetrahydro,2/3/4/5/tetrabromo-quateraddition
1/ 11
N,2/2/3/4/hexahydro-teraddition
or perhydroaddition
I/
1/N
,2121 C ,3/C ,4/ C-hexahydro-teraddition
3 CH2aCHCN
-
HOCH2CH2CONH2
Speechlwriting:
1/1/N,3/trihydro,4/hydroxy,2/oxo-teraddition
Indexing:
I/
11
N
,3/ C-trihydro,4/
C-hydroxy,2/C-oxo-teraddition
4 CH2=CH-CH=CH-CH2-CH=CH2
-
CH3-CHCI-CH2rCHCI-CH2-CHCI-CH3
For indexing this must be named
as
two
separate transformations (a biaddition and
a
monoaddition).
For

speecwwriting it would be permissible, applying Rule 2.2.2.4, (but not obligatory) to name it
as:
tris
-(hydro,chloro-addition)
3
ELIMINATION TRANSFORMATIONS
3.1
atoms or groups (called eliminands) are detached geminally (to form a carbene, nitrene, etc.), vicinally (to form
an
olefin,
a
carbonyl group,
an
imine, etc.), from positions which are separated by one atom (to form certain reactive
intermediates), or from positions separated by more than one atom (e.g., to form a conjugated diene). Elimination
from
two
vicinal positions joined by a double bond (to form a triple bond between those positions) is embraced.
Detachment of atoms or groups from positions separated by methylene groups, ether bridges and the like,
accompanied by bonding of those positions to each other
so
as
to form
a
ring structure of three or more ring members,
is excluded.
(Note. During the development of these rules, names such
as
“dehydrobromination” (which has appeared to some
extent

in
the literature) and
“de-hydro-de-bromination”
were considered but were rejected because to the ear and even
to the eye they closely resemble “hydro-de-bromination” which represents
a
substitution transformation. The usage
that has been adopted,
“hydro,bromo-elimination”,
is distinctive and self-explanatory.)
3.1.1
Elimination to form
a
single olefinic
or
acetylenic linkage.
3.1.1.1
The name comprises (a) the locant 11 and the name of the eliminand of lower priority
as
defined in Rule
0.2, (b) the locant 21 and the name of the eliminand of higher priority, and (c) the suffix “-elimination”. Groups are
named according
to
Rule 1.1.4.
Elimination
of
two univalent groups. These rules deal with transformations
in
which two univalent
742

COMMISSION
ON
PHYSICAL
ORGANIC CHEMISTRY
3.1.1
.2
If the
two
eliminands are the same, the name comprises (a) the locants 1/2/, (b) the syllable “di”
or
“bis”
(as
appropriate; see ref.
6),
(c) the name
of
the eliminand and (d)
the
suffix “-elimination”.
3.1.1.3
In
speecWwriting names the locants 1/ and
2/
and the hyphens may be omitted.
Examples:
1
(zn)
II
Br
Br

CH,-CH-C( CH3)2
-
CH3CH=C(CH&
SpeecWwriting: dibromoelimination
Indexing: 1/2/dibromo-elimination
2 CH3CH2CH2-CH-CH3
-
CH3CH2CH2CH-CH2
I
NMe3’
SpeecWwriting:
hydro,[trimethylammonio]-elimination
Indexing:
lihydro,2/[trimethylammonio]-elimination
3
CF~~CHPCCI-OCF~
-
CF3-CsCCl
SpeecWwritmg: specific:
hydro,trifluoromethoxy-elimination
Indexing: specific:
l/hydro,2/trifluoromethoxy-elimination
generic:
hydro,alkoxy-elimination
generic:
l/hydro,2/alkoxy-elimination
4a H
OSO2 C, H, CH3
4b
ditto

4d
dittn
4a
-
4d are all examples of the same transformation, namely:
Speech/writing: hydro,[
p
-tolylsulfonyloxy]-elimination
Indexing: l/hydro,2/[p
-tolylsulfonyloxy]-elimination
Variations
on
the name include:
For
4a and 4c: l/protio,2/[
p
-tolylsulfonyloxy]-elimination
For 4b and 4d: l/deuterio,Y[p
-tolylsulfonyloxy]-elimination
For 4a: (anti)-protio,[p
-tolylsulfonyloxy]-e1imination
5
(KO
WEtOH)
(Z)-CH3-CH=C-COCH3 CH3-C=C-COCH3
I
Br
SpeecWwriting: hydro,bromo-elimination
or
Indexing:

I/hydro,2/bromo-elimination
(anti)-hydro,bromc-elimination
Nomenclature for organic chemical transformations
743
3.1.2
Elimination to
form
a
multiple bond between carbon and an atom of another element.
Names are formulated
as
for elimination to form single olefinic linkages, except that names
of
the eliminands are
preceded by the italicised atomic symbols of the sites of elimination. When the eliminands are identical the substrate
sites are numbered in order of decreasing atomic number (Rule
0.3;
see example
3).
In speecWwriting, this site
designation may be omitted if the context makes clear the character of the transformation.
Examples:
1 CH3CH2-CH-OH
-
CH3CH2-CHO
I
SO3-
Speechlwriting:
0
-hydro- C-sulfonato-elimination

Indexing: 1/
0
-hydro,Z/C -sulfonato-elimination
2
PhCHzON02
__.*
PhCHO
Speechlwriting:
C-hydro,O-nitro-elimination
Indexing:
11
C
-hydro,2/0-nitro-elimination
3
(CH3)2CHOH
-
CH3COCH3
Speechlwriting:
0,
C-dihydro-elimination
Indexing:
I/
0,2/ C-dihydro-elimination
4
CH3CH2CH2-O-SMe2+
-
CH3CH2CH0
SpeecWwriting:
C-hydro,O-dimethylsulfonio-elimination
Indexing:

I/
C-hydro,2/0-dimethylsulfonio-elimination
or dihydroelimination (if the context indicates that
a
carbonyl group is formed)
5
Ph2CH-SCN
-
Ph2C-S
SpeecWwriting:
Indexing:
I/
C-hydro,Z/S -cyano-elimination
6
R-CH-N-OH
-
R-CsN
Speechlwriting:
Indexing:
1/C
-hydro,Z/N -hydroxy-elimination
7
R-C(-NH)OSOCI
-
RCsN
Note:
In
a relatively complicated example such
as
this it may be preferable not to use simplified

speecWwriting names.
C-hydro,S-cyano-elimination
or
hydro,cyano-elimination (to give
a
thione)
C-hydro,N-hydroxy-elimination
or
hydro,hydroxy-elimination
(from
an
oxime)
I/N-hydro,Y
C-[chlorosulfinyloxy]-elimination
3.1.3
single olefinic linkage except that for speecldwriting usually desirable to emphasize the character of the transformation
by including the locants
“I/”,
“I/”
and, for the formation of nitrenes, the atomic symbol.
(For
indexing they are
requisite.)
Examples:
Elimination to form
a
carbene
or
a
nitrene. The

rules
are the same
as
for elimination to form a
(base)
1 CHC13
-
C12C
2
RNH-OS02Ph
-
RN
lhydro, l/chloro-elimination 1/N-hydro,
1/N-[phenylsulfonyloxy]-elimination
3
CH212
-
CH2
I/
l/diiodo-elimination
3.1.4
Elimination to form
a
conjugated, cumulative
or
other extended unsaturated substrate.
3.1.4.1
If elimination occurs only from
two
adjacent atoms

or
from
a
single atom to form
a
carbene
or
nitrene, then
Rules
3.1.1
to
3.1.3
apply: the remainder of the unsaturated system is irrelevant
to
the name of the transformation.
Examples:
1 OH
I
(H+)
(CH3)2C-CH2COCH3
-
(CH,),C=CHCOCH,
hydro,hydroxy-elimination
or
l/hydro,2/hydroxy-elimination
(zn)
2 (CH3)2CBr-CO-Br
-
(CH3)2C-C-O
1/2/dibromo-elimination

3
Ph-CO-CH-N-Ph Ph-CO-C-N-Ph
I
-
II
Ph S02C&CH3 Ph
I/
C
-hydro,Z/N-[p
-toluenesulfonyl]-elimination
744
COMMISSION
ON
PHYSICAL ORGANIC CHEMISTRY
3.1.4.2
When the eliminands detach from sites that are separated by one
or
more atoms, then that part of the
substrate from which elimination occurs is numbered consecutively with post-slashed arabic numerals, atom 1/ being
the site from which the first-named eliminand is detached. With this modification, Rules 3.1.1 to 3.1.3 are then
applied. (Rule 3.1.1.3 is not applicable.) It is usually undesirable to omit atomic symbols for heteroatomic
substrates,
so
that indexing and speecldwriting names are identical.
Examples:
1
H OAc
I/hydro,4/acetoxy-elimination
3 (CH&$-C=CH
-

(CH&K=C=C
4
I
Cl
l/hydro,3/chloro-elimination
1/0,4/C-dihydro-elimination
+-
Ph-C-N-OH
-
[
Ph-C-N-0
+
Ph-C=N-O
]
I
c1
I/
O-hydro,3/C -chloro-elimination
3.2
Multivalent eliminations. Rules under this heading deal with transformations in which multivalent
eliminands
or
more than
two
univalent eliminands are detached to form a triple bond
or
a
conjugated or cumulative
unsaturated substrate. The multiplicity of these transformations is defined
as

one half of the combined valences of the
eliminands. Except for the usage described in Rules 3.2.1.2 and 3.2.2.2, simultaneous eliminations which generate
two or more isolated double bonds are regarded
as
separate transformations; each must be named separately.
The speech/writing names are the same
as
the indexing names unless otherwise stated.
3.2.1
eliminands,
or
of two divalent eliminands,
or
of one divalent and two univalent eliminands. The basic name
comprises (a) the names of the eliminands in order of increasing valence, groups of the same valence being given in
order of increasing priority
as
defined in Rule 0.2, each name being preceded by the appropriate site designation, and
(b) the
sumX
“-bielimination”.
3.2.1.1
If the first-named eliminand (if divalent)
or
the first
two
(if univalent) detach from position 1/ and the
remaining eliminand or eliminands detach from position 2/, then in the speecldwriting names the positional numbers
may optionally be omitted. In speech/writing the symbol
C

may be omitted if
no
ambiguity ensues.
3.2.1.2
If
a
bielimination involves the elimination of
two
identical pairs of univalent eliminands to form two
non-
cumulative double bonds, each between an identical pair
of
atoms, then in speech/writing only it may
be
named by
using the italicised prefix
“
bis
-”
followed in parentheses by the name of the corresponding monoelimination
as
described in Rule 3.1. This form of nomenclature may, if desired, be extended
to
include simultaneous eliminations
which form isolated double bonds. (Compare Examples 3,9.)
3.2.2
bieliminations with appropriate changes to the multiplying prefixes. Eliminations of multiplicity three, four, five, etc,
are named tereliminations, quatereliminations, quinqeliminations, etc, respectively.
3.2.2.1
If the atom designated

1/
is the only heteroatom from which eliminands detach, then for speech/writing the
symbol
C
for the other atoms may be omitted.
3.2.2.2
The usage described in Rule 3.2.1.2 may be extended to eliminations which form more than two
non-
cumulative double bonds by using the appropriate numerical prefix,
“
fhs-”,
“tetrakis-”,
etc. (See example 9.)
Examples:
Eliminations
of
multiplicity two (bieliminations). These are eliminations of four univalent
Eliminations
of
multiplicity greater than two arenamed byanalogywith the Rule (3.2.1) for
(NH2-)
1 EtCH2CHBr2
9
EtC=CH
Speecldwriting:
dihydro,dibromo-bielimination
Indexing:
l/l/dihydro,2/2/dibromo-bielimination
2
(NH2-)

CzH5CHBrCHzBr
-
QH5CCH
1 /2/dihydro, 1/2/dibromo-bielimination
Note. The omission of locants is not desirable in writing (Rule 3.2.1. l), but in speech it may be
permissible when it is obvious from the context what is meant.
3
(NH27
BICH~CH~CH~CH~B~
9
CH2-CH-CHzCH2
2/3/dihydro,
1/4/dibromo-bielimination
bis
-(hydrobromo)elimination (speech/writing only)
Nomenclature for organic chemical transformations
745
4 (NEt2-1
PhCHzCBrZCHzPh
-
PhCHIC-CHPh
1/3/dihydro,2/2/dibromo-bielimination
5
Ph-C-C-Ph
-
Ph-CPC-Ph
II
II
Nz Nz
Speechlwriting: bisdiazo-bielimination

Indexing:
1/2/bisdiazo-bielimination
Note the
use
of “bis” (unitalicised,
as
in
structural nomenclature)
as
a
multiplier for
a
group whose name
begins with a numerical prefix,
in
order to avoid “didiazo”. This
is
distinct from italicised
“
bis-
”
as
described in Rule 3.2.1.2 and illustrated in Example 3 above, to describe
a
multiple transformation.
6
CHzOH
I
CHO
I

~HOH
-
CH
I
II
I
CH20H CHz
Speechlwriting:
11
0,2/dihydro,3/4/dihydroxy-bielimination
Indexing:
11 0,2/C -dihydro,3/C
,4/
C-dihydroxy-bielimination
7
CH3CONH2
-
CH3CN
Speechlwriting:
NN-dihydro,C-0x0-bielimination
Indexing: 11 11 N-dihydro,Z/ C-0x0-bielimination
Note: The optional omission of the letter
C
from the speechlwriting name is not recommended in this
example; the emphasis of
NN
at the beginning of the name needs to be counteracted.
8
(CONHZ)~
-

NC-CN
11
11
N,4/4/ N-tetrahydro,ZIC ,3/
C-dioxo-quaterelimination
9
P~CH~-CHOH-CHZCHZ-CHOH-CH,-CHOH-CH~
-
PhCH-CH-CH2CH2-CH-CH-CH-CH2
For indexing this must be named
as
two separate transformations,
a
monoelimination plus a bielimination.
For
speechlwriting it is permissible, applying Rule 3.2.2.2, (but not obligatory) to name it
as:
tris-(hydro,hydroxy-elimination)
4
ATTACH
ME
NT AND DETACHMENT TRANSFORMATIONS
Attachment is a transformation under which the substrate is converted into another entity by the formation of one (and
only one) two-centre bond (single
or
multiple) between the substrate and another entity, with
no
other changes in
connectivity
in

the substrate. The origin of the entity that becomes attached to the substrate is not relevant to naming
the transformation. Detachment
is
the reverse of attachment.
In
general the names of these transformations are the
same for speechlwriting
as
for indexing, but more specific alternatives to the name “attachment” (for example,
“coordination”
or
“colligation”)
or
“detachment” (for example, “heterolysis”
or
“homolysis”) are permitted for
speechlwriting when they are consistent with common usage.
4.1
Attachment transformations. The name for these transformations comprises (a) the name of the entity
that becomes attached to the substrate, followed by (b) the suffix “-attachment”.
4.1.1
Naming of entities attached. The entity that becomes attached is named to balance the net charge
encountered in the transformation. Thus, for transformations in which bromomethane
is
formed from the substrates
H3C+, HJC’, and H3C-, the entities that become attached are bromide, bromine, and bromanylium, respectively,
regardless of their
origin.
An
entity may be named in

a
way that describes the site within it at which it becomes attached to the substrate, even
though that is not the way in which the isolated entity would be named. Ambident ions and radicals may be named
as
if they had the particular structures that obtain
in
the product (compare Table
1
and examples
9
and 10) and parenthetic
locants may be placed before the names of attaching entities to show the site of attachment (example 1 lb).
Examples:
1 Ph3C’
-
Ph3C-OH
hydroxide-attachment
(Note that the
tmsfomation
of Ph$+ to Ph3C-OH
is
constant, though the
reaction
may be camed out
in various ways, for example using HO-
or
HzO
or
HOC02-
as

reagent.)
‘Note that connectivity is not related to bond order (reference 2, p. 1304).
For
example, in the attachment of
Br-
to
the allyl cation there are changes in the
II
bond order within the allyl moiety, but the only change in connectivity is
the formation of the C-Br bond.
746
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
2
CH3CO2-
-
CH3COOH
0-hydron-attachment
3
Me3P
-
Me3P-0
P-oxygen-attachment
4 ArN2’
-
ArN-N-0-
N-oxide-attachment
5a Me$
-
H2C-SMe2 5b CH2
-

H2C=SMe2
S-methylene-attachment [dimethyl sulfide]-attachment
(Note that the
reaction
of Me$ with CH2 can be named
as
two
alternative attachment transformations.
However, whereas Me$
+
CH2N2 is an attachment if dimethyl sulfide is taken
as
the substrate, it is a
substitution
transformation of diazomethane.)
6a
C6H5.’
-
C&Br
bromine-attachment
+-
7
Ph2C-0
-
Ph2C4-AlC13
0-trichloroaluminium-attachment
8
(CH,),C+
-
(CH,),C-NCO

isoc
yanate-attachment
(Rule 4.1.1: “isocyanate” is used to signify attachment of the cyanate fragment via the nitrogen atom.)
9
Ph, C’
(Phj
C
*I
.
Ph2CaH
-
CPh,
There are
two
separate transformations in this example:
triphenylmethyl-attachment
(to C-4’ of the triphenylmethyl radical)
4-(diphenylmethylene)-cyclohexa-2,5-dienyl-attachment
(to C- 1 of the triphenylmethyl radical)
1
Oa H 10b H
1
-methylallyl-attachment
but-2-en-1-yl-attachment
1 la 1 lb
benzene-attachment
I
C1
(3)chlorobenzene-attachment
4.2

entity that becomes detached from the substrate, followed by (b) the
suffix
“-detachment”.
4.2.1
encountered
in
the transformation (compare Rule 4.1.1).
Examples:
Detachment Transformations. The name for these transformations comprises (a) the name of the
Naming of Entities Detached. The entity that
has
been detached is named to balance the net charge
1 CH3COOH
-
CH3C02-
0
-hydron-detachment
2
Ph-N=N-OH
-
Ph-N2+
N-hydroxide-detachment
3
[Cp(C0)2FeCH2OMq]+
-
[Cp(C0)2FeCH21+ 4
[dimethyl ether]-detachment
bromanylium-detachment
5
(CH3)3C-OCOCH3

__*
(CH,),C+
6
NzCHCOOEt
-
:CHCOOEt
acetate-detachment
or
ethanoate-detachment [dinitrogenl-detachment
7
CH3-CH2’
-
CH2-CH2
hydrogen-detachment
or
monohydrogen-detachment
Nomenclature
for
organic chemical transformations
747
5
SIMPLE REARRANGEMENT TRANSFORMATIONS
5.1
Scope
of the rule
The transformations named by these
rules
are those in which
a
group changes its point of attachment, whether

or
not
accompanied by any other transformation. Allylic rearrangements are not included they are covered by Rule 1.4.
Rearrangements associated with ring opening
or
closing are treated under Rule
8.
More complex rearrangements
appear
in
the list of complex transformations appended to these Rules.
In none
of
the transformations named by this rule are changes in the location
of
n-bonds
specifically described in the
name of the transformation.
5.2
5.2.1
group departs (which is given the locant
1/)
and that to which it moves, separated by an arrow
( ),
(b)
the name of
the migrating group, and (c) the suffix “-migration”. In speech the arrow
symbol
is pronounced “to”.
Examples:

Migrations unaccompanied by any other transformations.
Single migrations. The name comprises: (a) the site designations for the site from which the migrating
1
Me3N+-O-
-
MezN-OMe
l/N-2/0-methyl-migration
2 Pr3B C=O+
-
Pr2B-CO-Pr
Speecldwriting:
1/B
-
2/propyl-migration
Indexing:
1/B
-2/ C-propyl-migration
3 PhC-CH2
__*
PhC CHz
II
I
0
Me
I
OMe
Speecldwriting:
1/0 3/rnethyl-migration
Indexing: 1/04 3/C-methyl-migration
Interchange migrations. These are rearrangements in which

two
groups interchange their points of
5.2.2
attachment. The name comprises: (a) the name of the migrating group of lower priority, preceded by the site
designation
1/,
(b) the name of the migrating group of higher priority, preceded by its initial site designation, and (c)
the suffix “-interchange”.
Examples:
1
Ph3C-CO-Me
-
Ph2CMe-CO-Ph
l/methyl,2/phenyl-interchange
2 MeN-CH2CH2-0
-
MeN-CH2CH2-0
I
Ac
I
I
I
Ac H
H
1/
0
-hydro,4/N-acetyl-interchge
3a RCH-CH2CH2CH2-NR’
-
RCH-CH~CH~CHZ-NR

I
I
I
I
H C1 C1 H
c1
Both transformations are examples of 1/C
-hydro,5/N-chloro-interchange
5.2.3
migrating groups do not simply exchange their positions, the transformation is named
as
a
multi-migration,
as
in the
following example:
Example:
PhzC-CMe
-
PhC-CMePh
Other multiple migrations. If more than one migration occurs within the transformation and the
I
II
II
I
HO
0
0
OH
110

-410
-hydro,2/C-3/C-phenyl- bis-migration
748
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
5.3
[x,y] Sigmatropic rearrangements (where x, y
+
1). The names of these transformations take the
form: (a-b) (c-d)-sigma -migration, where a and b are the locants of the sites initially connected by the migrating
sigma bond, and c and d are the locants of the sites to which it moves.
(Note 1: The use
of
the term “sigmatropic” in this rule has
no
mechanistic significance.)
(Note 2: Sigmatropic hydrogen shifts and other
[
1 ,XI rearrangements are named according to Rule 5.2.1
.)
5.3.1
number of atoms across which the ends of the migrating sigma bond move. (See Example 2.)
5.3.2
substrates. (See Example 3.)
Examples:
1
In
casual use in speech/writing the form
[
x,y]
sigma

-migration may be used, where x and y represent the
In
speech/writing atomic
symbols
may be omitted in the context of comparison with homoatomic
6-a
3-6
l/+S/hydrogen-migration (Rule 5.2.1)
2
(3/4/)-( 1/6/)-
sigma
-migration
[3,3]sigma-migration (casual usage)
Speedwriting: (3/
0-4/)-(
1/6/)-sigma-migration
or, for comparison with an all-carbon substrate:
or (casually) [3,3]sigma-migration
(3/4/)+( 1/6/)-sigma -migration
Indexing:
(3/0-4/C) (l/C-6/C)-sigma-migration
Note in Examples 2 and 3 that the locants are derived by numbering along
a
chain that is continuous in the
substrate: Rule 0.3(a) is inapplicable, and the direction of numbering is determined from Rule 0.3(b,c).
5.4
rearrangement, with the following modifications: (a) the site of the incoming group
is
designated relative to that of the
leaving group, taken

as
l/); (b) the italicised prefix
“migro-”
is inserted before “substitution”; (c) the migration is
described by placing in parentheses immediately before
“migro-”:
(i) the locants of the sites from which the migrating
group departs and to which it moves, separated by an arrow
(+),
and (ii) the name of the migrating group.
5.4.1
In
speech/writing the term
“cine”
may be used
in
place of “(2/- 1hydro)-migro”; in such
cases
the
initial locant 2/ may be omitted. This usage is common for aromatic substrates but need not be confined to them.
Examples:
Migration accompanied by substitution. The name is based
on
that for substitution without
1
CH3CH2CH2Br
-
CH3CHCH3
I
Ph

Speech/writing:
phenyl-de-bromo-cine-substitution
Indexing: 2/phenyl-de-bromo-( 2/- 1hydro)-migro -substitution
2 CH3COCH2C1
-
EtOCOCH2CH3
2/ethoxy-de-chloro-(2/+ Urnethyl)-migro -substitution
CH3
I
CH3
I
3
Br
Speedwriting:
amino-de-bromo-cine-substitution
Indexing: 2/amino-de-bromo-( 2/-
1hydro)-migro-substitution
Nomenclature for organic chemical transformations
749
5.5
Migration accompanied
by
addition, elimination, attachment, detachment,
or
other
transformation. The name is
based
on
that of the transformation without rearrangement, with the following
modifications: (a) the italicised prefix

“mie-”
is inserted before the characteristic
suffix
that defines the type of
transformation; (b) the migration is described by placing in parentheses, immediately before
“migro-”:
(i) the site
designations of the sites from which the migrating group departs and to which it moves, separated by an arrow
(+),
and (ii) the name of the migrating group.
Examples:
1
Ph-CO-CO-Ph
-
Ph2C(OH)C02-
Speecwwriting: 1/ O-hydro-Yoxido-( 1/-2/phenyl)-migro -addition
Indexing:
2 Me3C-CH2Cl
-
Me2C-CHMe
1/ 0-hydro-3/ C-oxido-( l/C+2/C-phenyl)-migro -addition
lhydro, l/chloro-(2/-
llmethy1)-migro-elimination
3
Me2C-CMe2
-
Me$-CO-Me
II
HO OH
SpeecWwriting:

Indexing:
4 Me-CO-CHN2
-
O=C=CHMe
1
/
0
-hydro, 3/hydroxy-( 2/- 3/methyl)-migro -elimination
1/
0
-hydro,3/ C-hydroxy-( 2/
C

3lC -methyl)-migm -elimination
dinitrogen-( 2/- Urnethyl)-migm -detachment
5
(PhCH2)dN’
-
PhCH2CHPh-N(CH2Ph)2
Speech/writing: hydron-( 2/N- l/benzyl)-migro -detachment
Indexing: hydron-(2/N+ l/C-benzyl)-migro -detachment
6
COUPLING AND UNCOUPLING TRANSFORMATIONS
6.1
Scope of the Rule
This rule
is
designed to cover transformations such
as
2

A-B
-
A2. This could formally be named according to
Rule
2
as
a substitution, “A-de-B-substitution”, but such a name disguises the symmetry of the transformation. To
emphasise this, the “coupling” nomenclature is used. Likewise, A2
-
2 A could be named by Rule 4.2
“A-detachment”, but again the symmetry can
be
described better by using a special “uncoupling” nomenclature.
(Compare also the discussion of “aggregating” substitutions, Rule 1.3.)
Note that this rule is applicable only to truly symmetrical transformations.
For
example 2 Ph-Br
-
Ph2 is
a
coupling. 2 Ph-N2+
-
Ph-N-N-Ph is not, because the nitrogen atoms of the product do not derive symmetrically
from the substrate. Such
a
transformation should be represented
as
Ph-N2+
-
Ph-N-N-Ph (since only one of the

diazonium entities is
a
substrate) and named according to Rules 1
or
2
as
“N-benzenide-attachment”
or
“phenylazo-
de-diazonio-substitution”.
A transformation may be regarded
as
symmetrical at different levels of generality. Thus
Ph-Cl
+
Ph-Br
-
Phz,
a
reaction
in which the different halogens are specified, cannot be described
as
a
symmetrical
transformation
:
however, 2 Ph-Hal
-
Ph2 is symmetrical
at

the generic level. Likewise C&Br
+
CH3C6%Br
-
C6H+6%-CH3 is not
a
coupling transformation, though it belongs to the general class of
couplings represented by 2ArBr
-
Ar2.
For
a transformation to be treated
as
a
coupling, the substrate must appear
with the stoicheiometric coefficient of 2, the product must be symmetrical about a newly formed bond, and the two
half-product moieties must be of equal provenance. To be treated
as
an uncoupling the substrate must be symmetrical
about
a
bond that is cleaved, and the product must appear with the stoicheiometric coefficient of
2.
In
most of these transformations the symmetry requires that an attaching
or
detaching entity
be
given a name
appropriate to

a
particular oxidation level (see Table 1). Thus in Example 1 of Rule 6.2.1 the
tmsfonnation
of
2PhBr into Phz, regardless of the mechanism of the actual reaction, must
be
described in terms of the detachment of a
bromine
atom
from each substrate molecule and the coupling of the resulting phenyl radicals. However, when more
than one group is detached (Example
8,
Rule 6.2.1)
or
attached (Example, Rule 6.3.2),
or
when groups are both
attached and detached (Example
I,
Rule 6.4), there is
no
implied oxidation level and group names (Table 1) are
appropriate.
6.2
Coupling transformations with detachment. These are transformations in which one
or
more
univalent
or
multivalent groups

or
entities are detached identically from each of the
two
substrate entities and the
remaining fragments of the substrate become coupled.